Life History of Two Plastic Species of Polygonum; Their Economic Role

The fruits of Polygonum coccineum Muhl. and P. natans A. Eaton constitute an important source of food for waterfowl. Both species, particularly P. coccineum, commonly invade crops. Both are widely distributed in Iowa, and have been observed in the field in several forms and varieties: P. natans forma genuinum (A. Eaton) Stanford, and forma Hartwrightii (Gray) Stanford; P. Coccineum forma terrestrae (Willd.) Stanford, forma natans (Wiegand) Stanford, and var. pratincola (Greene) Stanford. The several forms of either species may occur on the single rootstock growing in dry ground bordering ponds. Each species has been converted from terrestrial to aquatic form under experimental control. All forms or varieties fruit under conditions of sufficient moisture. Polygonum natans shows less plasticity of root system than does P. coccineum which invades uplands. There the root system penetrates the soil 12 or more feet, but in aquatic stations only 12 to 18 inches